Effects of crumb rubber variability on failure temperature of Crumb Rubber Modified binders

Failure temperature of an asphalt binder is one of the criteria used when assigning a performance grade to the binder. Previous studies have shown that the modification of the binder with crumb rubber improves the high temperature properties. This paper investigates the effects of different crumb rubber sources on Crumb Rubber Modified (CRM) binder failure temperatures as defined by SHRP testing procedures. The objectives of this research were to identify crumb rubber properties affecting the rutting susceptibility of the CRM binders. The properties of four crumb rubber sources were identified by: grinding procedure (ambient and cryogenic), elemental analysis by Scanning Electron Microscope (SEM), and glass transition temperature by Differential Scanning Calorimeter (DSC). Findings suggest that ambient ground particles yielded the highest G*/sin delta values, while the elemental composition of the crumb rubber exhibited only a limited effect on the G*/sin delta.